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| Presentation | 2009-10-22 10:10 [Special Talk] Biomagnetic field measurements and EMI -- Active magnetic shielding, and observation and reduction methods of conducted EMI -- Ichiro Sasada (Kyushu Univ.) Link to ES Tech. Rep. Archives:  MW2009-93 |
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| Abstract | (in Japanese) | (See Japanese page) |
| (in English) | Abstract Magnetic fields from a human heart and a human brain are very small. They are on the order of several tens of pT for the former and sub-pT for the latter. They are time-varying signals having main frequency spectra less than 30 Hz in which range there are relatively strong low-frequency environment magnetic noises as interferences. Magnetic shielding rooms are widely used for their measurements. However, not only they are heavy and expensive, but also there is a hight barrier at the door way of such rooms. In this report, active magnetic shielding methods are presented in which unlike a conventional active magnetic shielding highly permeable shells are combined with it in order to obtain a wide shielded volume with high shielding efficiency and holding an easy access way to the shielded space. Another topic in this report is conducted EMI problem encountered in operating a SQUID sensor used to measure biomagnetic fields with a cryocooler for cooling. The cold head of a cryocooler where a SQUID is located is linked to an inverter-driven valve motor with conducting horses, and the valve motor is further linked to an electrically noisy compressor housing with conducting horse and with a power line. We have analyzed conducting passes of noise currents by observing their waveforms simultaneously at several points using current transformers we made. Through the simultaneous observation of noises, we could easily locate the cause of conducted EMI and succeed to operate a SQUID after reduction of the influence of the EMI. | |
| Keyword | (in Japanese) | (See Japanese page) |
| (in English) | Active magnetic shielding / Biomagnetic fields / SQUID / Cryocooler / conducted EMI / Current transformer / / | |
| Reference Info. | IEICE Tech. Rep., vol. 109, pp. 1-6, Oct. 2009. | |
| Paper # | ||
| Date of Issue | 2009-10-15 (EMCJ, MW) | |
| ISSN | Print edition: ISSN 0913-5685 Online edition: ISSN 2432-6380 | |
| Copyright and reproduction |
All rights are reserved and no part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording, or any information storage and retrieval system, without permission in writing from the publisher. Notwithstanding, instructors are permitted to photocopy isolated articles for noncommercial classroom use without fee. (License No.: 10GA0019/12GB0052/13GB0056/17GB0034/18GB0034) | |
| Download PDF | Link to ES Tech. Rep. Archives: MW2009-93 |
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| Conference Information | |
| Committee | EMCJ MW IEE-MAG |
| Conference Date | 2009-10-22 - 2009-10-23 |
| Place (in Japanese) | (See Japanese page) |
| Place (in English) | Iwate Univ. |
| Topics (in Japanese) | (See Japanese page) |
| Topics (in English) | |
| Paper Information | |
| Registration To | IEE-MAG |
| Conference Code | 2009-10-EMCJ-MW-MAG |
| Language | Japanese |
| Title (in Japanese) | (See Japanese page) |
| Sub Title (in Japanese) | (See Japanese page) |
| Title (in English) | Biomagnetic field measurements and EMI |
| Sub Title (in English) | Active magnetic shielding, and observation and reduction methods of conducted EMI |
| Keyword(1) | Active magnetic shielding |
| Keyword(2) | Biomagnetic fields |
| Keyword(3) | SQUID |
| Keyword(4) | Cryocooler |
| Keyword(5) | conducted EMI |
| Keyword(6) | Current transformer |
| Keyword(7) | |
| Keyword(8) | |
| 1st Author's Name | Ichiro Sasada |
| 1st Author's Affiliation | Kyushu University (Kyushu Univ.) |
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| Speaker | Author-1 |
| Date Time | 2009-10-22 10:10:00 |
| Presentation Time | 30 minutes |
| Registration for | IEE-MAG |
| Paper # | EMCJ2009-44, MW2009-93 |
| Volume (vol) | vol.109 |
| Number (no) | no.241(EMCJ), no.242(MW) |
| Page | pp.1-6 |
| #Pages | 6 |
| Date of Issue | 2009-10-15 (EMCJ, MW) |
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